Finishing process

ABSTRACT

A method of finishing a workpiece is disclosed. The method includes the use of a container, preferably a drag finishing machine to displace a workpiece or part about a substantially vertically oriented axis. The workpiece is immersed in a media and an abrasive that adheres to the media via surface tension of a liquid disposed in the container or drag finisher. The workpiece is then displaced and the workpiece contacts or impacts the abrasive to provide the desired finishing. The abrasive may move from media to media as it is loosely attached via the surface tension of the liquid.

BACKGROUND OF THE INVENTION

This invention generally relates to a method for finishing parts. More particularly, this invention relates to displacing a workpiece within and relative to media and an abrasive.

U.S. Pat. No. 5,251,409 discloses a method of drag finishing a housing that comprises lowering a workpiece or housing into media. When the housing is in the media, the housing is revolved in a first rotational direction about a vertical axis and also moved in first angular direction about a vertical axis. Then the housing is also revolved in a direction opposite to the first rotational direction, and moved in a second angular direction.

U.S. Pat. No. 6,261,154 discloses a method and apparatus for media finishing. The workpiece or wheel is angularly displaced while being rotated about an oblique angle.

Advances in the drag finishing arts include the method of moving a workpiece relative to the tub and media within the tub. The prior art also includes processes that utilize media and abrasive additives in vibratory and barrel finishing machines.

Processes utilizing media and abrasives or abrasive additives have been used in the past in vibratory and barrel finishing processes to refine the surfaces and smooth the surfaces of parts or workpieces. Use of the vibratory or barrel finishing processes may be useful to reduce the surfaces of about 5 micro-inches to about 50 micro-inches. This process may take about 10 hours to 20 hours to complete.

A drag finishing process has been used to recover the surfaces of workpieces that incurred surface degradation or surface roughness of about 10 RA micro-inches to about 15 RA micro-inches, from a prior operation, for cosmetic or bearing surface purposes.

As can be seen, there is a need for improved apparatus and methods in the media that is disposed in the tubs used in the drag finishing apparatus and method. There is a need to reduce (1) processing costs, (2) the amount of media used, (3) the amount of solids (effluent) required to be treated, (4) disposal costs of the used media solids (effluent), (5) the amount of solids that are required to be sent to a land fill, and (6) multiple step finishing operations. There is also a need to accelerate the finishing and stock removal rate.

There is also a need to reduce surfaces from between about 150 RA micro-inches to about 5 RA micro-inches. Surface roughness can be measured by a profilometer, which is a stylus device used to trace across the surface profile. The results are expressed either as RA, which is the arithmetic average deviation from the center line of the surface, or as RMS, which is the root mean square of the deviations from the center line. RA or RMS values are given in either microns (same as micrometers or μm) or micro-inches (μ). Typically RMS may be about 11 percent higher than the RA number for a given surface.

SUMMARY OF THE INVENTION

One aspect of the present invention is a method of finishing a workpiece, comprising: providing a container; providing a media disposed within said container; providing an abrasive disposed within said container, said abrasive capable of adhering to said media to form a media-abrasive mixture; and displacing the workpiece within said media-abrasive mixture.

Another aspect of the present invention is a method of finishing a workpiece, comprising: providing a drag finishing machine; providing a media disposed within said drag finishing machine; providing an abrasive disposed within said drag finishing machine, said abrasive capable of adhering to said media to form a media-abrasive mixture; and displacing the workpiece within said drag finishing machine.

Another aspect of the present invention is a method of finishing a workpiece, comprising: providing a container; providing a media disposed within said container; providing an abrasive disposed within said container, said abrasive capable of adhering to said media to form a media-abrasive mixture; and displacing the workpiece within said container.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective of one exemplary embodiment of a container;

FIG. 2 illustrates an abrasive and a media forming a media-abrasive mixture; and

FIG. 3, illustrates the steps of the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

The process of the present invention utilizes the combination of (1) a media 20 and (2) an abrasive 30.

The process involves displacing a workpiece 10 relative to the media 20 and abrasive 30. The media 20, abrasive 30, and workpiece 10 are disposed in a container 40. In one exemplar embodiment of the present invention, the container 40 is a drag finisher.

In one exemplary embodiment, the media 20 may be either a preformed media 20, a random media 20, a metallic media 20, or it may be a cast shape or a metal punching. One exemplary embodiment of the preformed media 20 is preformed ceramic media 20 or a preformed porcelain media 20.

As a workpiece 10 is displaced within the media 20, the media 20 exerts pressure on the abrasive 30, which contacts the workpiece 10 for finishing as the workpiece 10 moves through and past the media 20. The media 20 acts as a carrier for the abrasive 30. The cutting or metal removal function may be caused by the media 20 carrying or grinding the abrasive 30 between the media 20 and the workpiece 10. The media 20 may contact the workpiece 10 and cause incidental finishing. The abrasive 30 may have one or a plurality of sharp edges 60 that are used to finish the workpiece 10.

In one exemplary embodiment the abrasive 30 or abrasive additive 30 may be a fused aluminum oxide, silicon dioxide, diamond powders, zirconia, or quartz. The types of abrasives 30 can be altered to achieve the desired effects and assist in the efficiency of the process. The abrasive 30 size may vary depending on the desired breakdown rate of the abrasive 30. The breakdown rate is its effective life of usefulness as an abrasive 30. Throughout use the abrasive 30 may become smoother. In other words, the abrasive 30 in its new or virgin state may be more aggressive and may impart a deeper cut pattern into the workpiece 10 surface. However, as the loose abrasive 30 wears down, its cutting ability may be reduced, which may impart a smoother surface or a shallower cut or scratch into the workpiece 10. In one exemplary embodiment of the present invention the abrasive 30 may have an ANSI grit size of about 150 grit or coarser. In one exemplary embodiment, the ANSI grit size by be about 60 to about 220. The abrasive 30 may be either dry or viscous.

In one exemplary embodiment of the present invention, renewal of the cutting ability through out the process cycle may be accomplished by either a periodic or a continuous addition of the abrasive 30 or abrasive additive 30 to the media 20. In one exemplary embodiment of the present invention the abrasive 30 may be added either continuously or intermittingly, and then addition of the abrasive may cease towards the end of the process cycle, to allow coarser abrasives to wear down or erode, thus imparting a smoother finishing as the size of the abrasive 30 degrades or becomes finer. In one exemplary embodiment of the present invention, one may start the process cycle with coarser abrasives to provide for faster stock removal than the prior art, and then add finer or different abrasives 30 towards the end of the process cycle.

It may be important to use the media 20, or media mass 20 with respect to the final finishing capability of the abrasive 30 characteristic of the preformed media 20, media 20, or media mass 20. This may be because the content level of the abrasive 30 of the media 20 may allow the final step or steps of the process cycle to achieve the desired surface condition of the workpiece 10. This may also be because the shape of the media 20 may provide the maximum efficiency for the media 20 to carry the abrasive 30 to contact the workpiece 10 or part 10.

In one exemplary embodiment of the present invention the abrasive 30, additive 30, or abrasive additive 30 may adhere to the media 20 by the surface tension created by the addition sufficient amounts of a liquid 50, such as water 50 or a finishing compound 50.

In one exemplary embodiment of the present invention, the media 20, abrasive 30, and workpiece 10 may be disposed in a container 40, whereby the workpiece 10 may be displaced to create a force between the abrasive 30 and the workpiece 10. The abrasive 30 may adhere to the media 20 via the surface tension of a liquid 50. Some abrasive 30 may be loose, i.e. may not be adhered to the media 20. In one exemplary embodiment of the present invention the container 40 may be a high energy machine 40, such as a plunge machine 40. In one exemplary embodiment of the present invention the container 40 may be a drag finisher 40. In one exemplary embodiment, the drag finisher 40 may be a machine that has a “Lazy Susan”-like spinner, which has a series of parts hanging on stations or fixtures below. The spinner then lowers the workpiece 10 into the media 20-abrasive 30 mixture as the workpiece 10 moves or revolves, or it can held statically and displaced around a vertical axis, into a bed of media 20-abrasive 30 mixture that is contained in an annular ring bowl. As the workpiece 10 “plows” through the media 20-abrasive 30 mixture, the process accomplishes its prescribed or desired work objective, depending on the selected media 20 and abrasive 30. The drag finishing machine 40 and process may accomplish the desired pressure and velocity by displacing the workpiece 10 relative to the container 40 at velocities or angular velocities of about 300 to about 500 or more feet per minute. In one exemplary embodiment of the present invention utilizing a drag finisher 40 may speed up the finishing process by about 20 to about 40 times as compared with a vibratory finisher. For example, what may take only about less than two hours when using a drag finisher may take 24 hours or more when using a vibratory finisher.

The present invention may use different types of containers 40. In one exemplary embodiment of the present invention, the container 40 may pull, push, or drag the workpiece 10 in either a statically held position or in a rotational movement through the media 20 and abrasive 30.

In one exemplary embodiment of the present invention, desired material removal or metal removal is accomplished by proper sizing of the abrasive 30 or the abrasive additive 30. In one exemplary embodiment of the present invention, a surface having about 150 RA micro-inches to about 5 RA micro-inches may be smoothly finished.

To remove the abrasive 30 from the media 20, copious amounts of liquid 50, such as water 50, may be added, which may break the surface tension and rinses the abrasive from the container 40 via a drain (not shown).

The steps of the present invention include providing a container 100, providing a media disposed within said container 200, providing an abrasive disposed within said container 300, and displacing the workpiece within said media-abrasive mixture 400. In one exemplary embodiment of the present invention, the steps need not take place in any specific order.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A method of finishing a workpiece, comprising: providing a container; providing a solid media disposed within said container; providing a solid abrasive disposed within said container, said solid abrasive having an ANSI grit size between about 60 to about 220, said solid abrasive adhering to said media to form a media-abrasive mixture said solid abrasive having different properties than that of the solid media; and displacing the workpiece within said media-abrasive mixture at speeds between about 300 feet per minute and about 500 feet per minute.
 2. The method of claim 1, wherein said container is a drag finishing machine.
 3. The method of claim 1, wherein said container is a plunge machine.
 4. The method of claim 1, wherein said media is at least one of a metallic media, ceramic media, or porcelain media.
 5. The method of claim 1, wherein said abrasive has a plurality of sharp edges.
 6. The method of claim 1, wherein said abrasive is at least one of an aluminum oxide, silicon dioxide, diamond powder, zirconia, or quartz.
 7. The method of claim 1, wherein said abrasive has a grit size of about 60 or coarser.
 8. (canceled)
 9. The method of claim 1, wherein said abrasive is dry.
 10. The method of claim 1, wherein said abrasive is viscous.
 11. A method of finishing a workpiece, comprising: providing a container; providing a solid media disposed within said container; providing a-solid abrasive disposed within said container, said solid abrasive having an ANSI grit size between about 60 to about 220, said solid abrasive capable of adhering to said media to form a media-abrasive mixture, and displacing the workpiece within said media-abrasive mixture at speeds between about 300 feet per minute and about 500 feet per minute, wherein a liquid is added to the media-abrasive mixture, and said abrasive adheres to said media via a surface tension of said liquid.
 12. (canceled)
 13. The method of claim 1, wherein the workpiece has and RA in micro-inches of between about 5 and about 150 before the workpiece is displaced relative to said container.
 14. The method of claim 1, wherein said media acts as a carrier of said abrasive.
 15. The method of claim 1, wherein said abrasive has a sharp edge.
 16. A method of finishing a workpiece, comprising: providing a drag finishing machine; providing a media disposed within said drag finishing machine; providing an abrasive disposed within said drag finishing machine, said abrasive having a different shape than that of the media, said abrasive adhering to said media to form a media-abrasive mixture; and displacing the workpiece within said drag finishing machine.
 17. A method of finishing a workpiece, comprising: providing a container; providing a media disposed within said container; providing an abrasive disposed within said container said abrasive having a different shape than that of the media, providing a liquid within said container, said liquid having a surface tension, said surface tension causing said abrasive to adhere to said media to form a media-abrasive mixture; and displacing the workpiece within said container. 